Deep water pumping method



Feb. 21, 1967 w. SWAN, JR 3,304,868

DEEP WATER PUMPING METHOD Filed July 31, 1964 /r)c0mpres$i/9/e Reco very hqu/o Sup 04y for? S /y A 10 De/wery A05 INVENTOR. W////0m 0. SWOHJJIT HTTORNEY United States Patent 3,304,868 DEEP WATER PUMPING METHOD William 0. Swan, Jr., Midland, Mich., assignor to The Pew Chemical Company, Midland, Mich., a corporation of Delaware Filed July 31, 1964, Ser. No. 386,653 5 Claims. (Cl. 103-1) This invention relates to a method of pumping and more particularly concerns a novel process for pumping and raising aqueous solutions and suspensions from great depths.

In deep Water pumping in the open ocean, and particularly in ocean bottom dredging, for example, it is undesirable to have a pump or other active instrumental equipment at the lower end of a delivery hose. Such a piece of equipment can be easily lost. In addition a pump located at great depths requires long electrical cables or other operating power sources and would have to be suitable for use at high ambient pressure.

Ordinarily, the air lift or percolator method of pumping is widely used in underwater pumping from maximum depths of several hundred feet. It is particularly effective in shallow water and sludge operations and is especial- 1y useful when large particulate matter is to be raised with the water from relatively shallow depths. This pumping method makes use ofcompressed air injected into a delivery hose at or near its lower end. The air lowers the specific gravity of the water in the delivery hose relative to that of the surrounding Water, and the resulting differential pressure causes upward flow of the water in the hose. Pumping energy is provided by an air compressor, which must deliver air at a pressure exceeding the water pressure at the depth where injection takes place.

When the air lif method is applied to water at depths greater than a few hundred feet below the surface, the method is inefficient and uneconomical primarily because the compressibility and solubility of air at high pressures reduces its buoyant effect.

It is a principal object of the instant invention to provide an eflicient method of pumping of water from great depths.

It is also an object of the present invention to provide an eflicient method of pumping water and particulate matter suspended therein from great depths as from an ocean bottom.

An additional object of the instant invention is to provide a method of pumping water from great depths using a substantially incompressible liquid to supply the buoyancy for lifting said water to the surface.

A further object of this invention is to provide a method of pumping Water from great depths in which the up going or delivery hose has substantially no pressure differential between its interior and the surrounding water, so that it may be fabricated of lightweight and/ or flexible wall material.

Other objects and advantages of the instant invention will become apparent from reading the detailed description set forth hereinafter in conjunction with the accompanying drawing in which:

The figure shows schematically one embodiment for carrying out the instant method.

In general the method of the instant invention of raising aqueous solutions, Water or such media having suspended particulate matter from great depths comprises immersing to the desired depth in the water body a delivery hose for delivery of Water to be recovered; injecting a substantially incompressible liquid into the delivery hose at a predetermined position, preferably near the end of said hose farthest from the surface of the water, said incompressible liquid having a specific gravity less than water thereby lowering the specific gravity of the liquid in the delivery hose relative to that of the surrounding water and lifting water up through said delivery hose. The Water and any particulate matter suspended therein can be recovered at the surface or otherwise handled, or utilized. The substantially incompressible liquid can be recovered from the water pumped and subsequently be recycled to the supply hose for reuse.

An advantage of the present novel process is that since the differential operating pressure caused by the specific gravity differential between that of the Water and the incompressible liquid is exactly balanced by the fluid friction within the hose, there is substantially no pressure difi'erential across the hose wall.

Referring to the embodiment of the figure a delivery hose 10 is immersed in water at one end 14 and attached at the other end 18 to recovery tank 20. A pump 22, in direct communication with an incompressible liquid supply source 26, has a liquid supply hose 30, which has a diameter smaller than that of the delivery hose immersed in the water so that end 34 of said liquid supply hose 30 is at, near, or attached to the end 14 of said delivery hose 10. When pump 22 pumps incompressible liquid down supply hose 30, the water and any particulate material in the vicinity of end 14 is buoyed up by said incompressible liquid and is thereby lifted up through delivery hose 10 to recovery tank 26.

In order to maintain a constant mixing of the pumping liquid and water the interior surface of the delivery hose preferably is roughened, irregular or otherwise fabricated so as to induce turbulence in the moving liquid.

The actual operating conditions for pumping liquid from a given depth are based on pumping pressure, liquid velocities and fluid head between the pumping liquid and the aqueous solution or water being pumped. In operability the minimum pressure under which the substantially incompressible pumping liquid is to be pumped down the supply hose is to be equal to the sum of the velocity head of the liquid in the supply hose and its static head in the supply hose and can be computed utilizing the following formula:

(1) f,Z,V,,

where:

f, is the friction factor in the supply hose, l is the supply hose length,

V is the liquid velocity down the hose,

a is the supply hose inner diameter,

g is the acceleration of gravity,

11 is the depth of the supply hose,

D is the density of the water,

D is the density of the substantially incompressible liquid.

The velocity (v of the incompressible liquid and water mixture in the delivery hose is then computed using the following formula:

2 0 d l d 1 f a a wherein:

Q, is the volume flow rate of the liquid in the supply hose and is equal to 3 f is the friction factor in the delivery hose, I is the delivery hose length, h is the depth of the delivery hose, d is the delivery hose inner diameter.

Equation 2 can be simplified to read as follows:

(3) -3 h. croft) TQT wherein:

Q: 3 dy dowwn Equation 4 can be simplified to read as follows:

In using the simplified Equations 3 and 5 d is expressed in inches, v is expressed in feet per second, Q is expressed in cubic feet per second.

Under typical practical conditions the use of Equations 3 and 5 to determine velocity and volume flow rate will produce results accurate to about 20 percent.

If the pumping liquid is supplied at such a rate that the velocity head in the supply hose equals the static head in the supply hose, which is a typical condition of operation,

then

Q )5 Q: s

and the total pressure at the top of the supply hose (P is equal to and In summary the minimum pressure needed to be maintained on the pumping liquid at the top of a supply hose to force the pumping liquid down the given supply hose can be determined by using Equation 1. The velocity and the volume flow rate of liquid up the delivery hose can be determined by using Equations 2 and 4.

The substantially incompressible liquid used to supply the buoyancy effect herein should have a specific gravity of less than about 1, and preferably a specific gravity of from about 0.8 to about 0.9. The liquid further is characterizcd as being essentially immiscible with water, so that there can be rapid recovery, and rapid agglomeration from the pumped water. Preferably the liquid should have a high float point, and have a low viscosity to provide for a low friction loss in the liquid supply hose. In addition, the liquid should have a low vapor pressure to reduce loss thereof and low water solute uptake so as to reduce corrosion and fouling of pump and liquid supply hose.

Examples of liquids suitable for use herein include kerosene, fuel oils, light weight lubricating oils, isopropylbenzene, diisopropylbenzene, diethylbenzene, 2-ethylhexyl acrylate, and the like organic liquids and mixtures thereof.

The following example is merely illustrative of the instant invention and in no way is meant to limit it thereto.

Example Using an apparatus similar to that shown in the figure, a five in-ch delivery hose connected at one end to a recovery tank is lowered to a depth of about 2000 feet in sea water (specific gravity 1.025). A one inch supply hose is connected at one end to a pump and at the other end to the submerged end of the delivery hose as shown. Diisopropylbenzene (specific gravity 0.865) is pumped down the 1 inch supply hose.

The operating conditions for the assembly to be used in raising water from the 2000 foot depth readily can be determined as follows:

we find that P =0.87 (2000) (1025-0865) or a minimum pressure of about 278 psi. is needed to pump the diisopropylbenzene down the supply hose. The volume flow rate of the diisopropylbenzene is obtained using the following equation: (7) Qi= 6 Z (6w6:)

Q =0.066 cu. ft./sec. or about 30 gal/min. The total flow rate in the delivery hose is determined from the equation Q: y/a Qt and is found to be about 0.965 cu. ft./sec. or about 438 gal/min.

Thus it is seen that 30 gal/min. of diisopropylbenzene fluid raises 408 gal/min. of sea water.

In a manner similar to the foregoing, if a delivery hose of about ten inches in diameter is employed, the total flow rate through the delivery hose is about 1390 gaL/ It is to be understood that any of the substantially incompressible liquids set forth hereinbefore can be employed in the present novel process to raise from great depths aqueous solutions water and such media having suspended solids therein.

Various modifications can be made in the instant invention without departing from the spirit or scope thereof for it is to be understood that I limit myself only as defined in the appended claims.

What is claimed is:

1. A method of pumping water from great depths which comprises:

(a) immersing a delivery hose into a body of water to the desired depth;

(b) immersing a supply hose into said water so that the end of said supply hose farthest from the waters surface is located at about the end of said delivery hose farthest from the waters surface, said supply hose having a smaller diameter than said delivery hose;

(c) injecting a substantially incompressible liquid into said supply hose under a pressure which is not less than P in accordance with the formula:

wherein:

f is the friction factor in the supply hose, I is the supply hose length, v is the liquid velocity down the supply hose, g is the acceleration of gravity, h is the depth of the supply hose, D is the density of the water, D is the density of the substantially incompressible liquid;

(d) lifting and pumping water through said delivery hose in a direction toward the surface of said Water at a velocity of v and a volume flow rate of Q calculated .by employing measured values in accordance with the following formulae:

wherein Q: is the volume flow rate of the liquid in the supply hose and is equal to and 2. The method in accordance with claim 1 wherein said Water to be raised contains particulate matter suspended therein.

3. The method in accordance with claim 1 including the steps of recovering said substantially incompressible liquid from the water and recycling said liquid to the supply hose.

4. The method in accordance with claim 1 wherein said water is sea Water and said substantially incompressible liquid is diisopropylbenzene.

5. The method in accordance with claim 1 wherein the interior surface of said delivery hose is roughened to induce turbulence in the moving liquid.

References Cited by the Examiner UNITED STATES PATENTS 1,741,571 12/ 19-29 Ives 103-2-32 2,046,434 7/1936 F ouhey 30214 2,559,404 7/ 1951 Cox 1032 2,686,085 8/ 1954 Odell 30266 LAURENCE V. EFNER, Primary Examiner. 

1. A METHOD OF PUMPING WATER FROM GREAT DEPTHS WHICH COMPRISES: (A) IMMERSING A DELIVERY HOSE INTO A BODY OF WATER TO THE DESIRED DEPTH; (B) IMMERSING A SUPPLY HOSE INTO SAID WATER SO THAT THE END OF SAID SUPPLY HOSE FARTHEST FROM THE WATER''S SURFACE IS LOCATED AT ABOUT THE END OF SAID DELIVERY HOSE FARTHEST FROM THE WATER''S SURFACE, SAID SUPPLY HOSE HAVING A SMALLER DIAMETER THAN SAID DELIVERY HOSE; (C) INJECTING A SUBSTANTIALLY INCOMPRESSIBLE LIQUID INTO SAID SUPPLY HOSE UNDER A PRESSURE WHICH IS NOT LESS THAN PS IN ACCORDANCE WITH THE FORMULA: 